When you live in a city, you can sense its pulse, experience its pace of life... City behavior is predictable over certain timescales, even though is the result of the seemingly independent decisions made by millions of different people.MIT Technology Review , 2013

Population’s movements, fruit of millions of individual decisions taken by many different motivations, have a disturbingly large coherence.
This scientists define the big laws that govern this apparent chaos.SCIENCE&VIE No. 1172, 2015